In applications where moving parts must be protected from excessive wear, hard coatings are often applied to components. The class of hard ceramic materials known as nitrides are often used for these coatings, but the performance of nitride coatings is limited and often insufficient, leading to breakdown of important components. New nitride materials have been predicted that are expected to have the significantly improved properties for wear resistance and corrosion resistance. Fabrication of these materials, however, remains a challenge. This award supports research to systematically determine the conditions that will enable the manufacture of these desired new nitride materials. The results of this research will accelerate discovery of hard, wear-resistant and corrosion-resistant coatings through a targeted synthesis approach, yielding new coating materials for emerging applications including fuel-efficient jet engines and gas turbines, environmentally-friendly lubricant-free cutting tools, high-temperature concentrating solar power plants, and wind turbines.
The coatings-by-design approach in this work facilitates the introduction of promising new nitrides, which have remained unexplored because the traditional approach of simultaneously optimizing composition, microstructure, and deposition process is too costly and slow. This method enables a deterministic pathway to ascertain the processing parameter space to achieve the desired composition and microstructure from thermodynamic and kinetic parameters, and then synthesize the coating experimentally. This method is based on an iterative combination of experiments and density functional theory calculations, to determine nitrogen incorporation kinetics and phase formation during deposition of transition metal nitride coatings. The research effort focuses primarily on the systematic determination of reaction and diffusion rates and local equilibria at the surface of growing transition metal nitride layers during coating synthesis. A quantitative model will be developed that predicts composition and phase of deposited nitrides as a function of incident ion energetics and growth temperature and pressure, using both measured and calculated values. The model will be verified by experimental coating deposition. Deposition of new super-hard, tough, and vacancy-stabilized nitride phases will be explored. Data collected in this research will be made publicly available through an open online database.
